Color display devices that include R, G, and B color LEDs as a plurality of light-emitting elements with different colors have been conventionally used, and shade correction devices and methods that correct the shade of the light emitted from LEDs have been proposed (e.g., see Patent Literature 1). The shade correction device described in Patent Literature 1 includes: a CPU that controls the lighting of LEDs; a ROM that stores, as tables, pieces of information regarding the values of currents flowing through R, G, and B LEDs; and a RAM that stores the values in one selected from the plurality of tables. This shade correction device is configured to correct the shade of the light emitted from the LEDs by selecting an optimal one of the tables.
Current control and pulse width modulation (PWM) control are known as methods of controlling the brightness of LEDs. In the PWM control, the duty ratio of a pulse waveform applied to each LED is changed whereby the brightness of the LEDs is modified. If the brightness of each color LED is changed to gradually modify a display color (e.g., fade in or fade out the display color), the relationship between the duty ratio and the changing time is used as a parameter for the PWM control. In general, a table that has been stored in, for example a ROM in advance is used as the above parameter. The changing rate of a duty ratio per time is defined in the table, and the brightness of each LED (display color) is modified on the basis of this changing ratio.